METHOD AND APPARATUS FOR RECYCLING WASTE CONTAINING PLASTIC AND/OR ORGANIC MATERIAL

Abstract: With the apparatus (10) described, all kinds of waste, particularly plastic waste, either truly sorted or randomly mixed, for instance plastic wastes from refrigerators to be disposed of, are broken down into their constituent parts and can then be reused. For this purpose microwave energy with a high energy density is admitted by means of magnetrons (28) to the waste (12) in the vacuum chamber (16) wherein a previously introduced gas such as argon is ionized, with the effect that gaseous constituents leave the waste (12) and build up a plasma under the action of the microwave energy, whereby the waste (12) is ultimately totally broken down. The plasma is ignited by the introduction of hydrogen into the vacuum chamber (16) containing the ionized gas. The waste (12) is reduced by the action of the plasma and hydrated by the hydrogen. Gaseous constituents of the waste (12) are removed via discharge lines (24, 26) and a liquid or powdery residue in a waste receptacle (13) is removed together with the same from the vacuum tank (14).

Description: METHOD AND APPARATUS FOR RECYCLING WASTE CONTAINING PLASTIC AND/OR ORGANIC MATERIAL Description Technical Field This invention refers to a method and an apparatus of the type given in the preamble of claims 1 and 6, respectively. Background Art Recycling waste consisting primarily of plastic, still creates tremendous problems today. On the one hand, with conventional methods only truly sorted plastic waste can be recycled, and on the other hand, a blowing agent of PUR in- sulating foam such as that used in refrigerators can not be removed and recovered with adequate thoroughness. A method and an apparatus for refrigerator disposal, the starting point for the present invention, is described, for example, in the leaflet "Kύhlschrank-Entsorgung, Modell Schleswig-Holstein, System Bresch" (refrigerator disposal, Schleswig-Holstein model, Bresch system) , issued by the na¬ tional guild association of the German refrigerating plant makers* trade in Dύsseldorf. To be sure, it is not indi- cated therein how the blowing agent is removed from the PUR insulating foam in refrigerator disposal; however it is known to the applicant that the PUR insulating foam is pressed to expel the blowing agent from it. This method is not sufficiently effective. In particular, it is un¬ suitable for breaking down waste containing plastic and/or organic material into its basic components. Disclosure of Invention The object of the invention is to design a more effective method and apparatus of the type given in the preamble of claims 1 and 6, respectively, in particular such that plas- tic waste of any composition can be broken down into its basic components and these components can be recovered. This object is carried out according to the invention with the steps and features given in claims 1 and 6, respec- tively. The waste recycled by means of the method and the apparatus according to the invention does not need to be sorted into its various constituents prior to the recycling, for ac- cording to the invention, solid and gaseous components are recovered separately in the recycling. The recovery of the gaseous basic components in this is virtually total, for which reason the method working with ionized gas and plasma according to the invention is superior to the mechanical method mentioned above. Advantageous embodiments of the invention form the subject matters of the subclaims. Brief Description of Drawings Two embodiments of the invention are depicted in the draw¬ ings and are described in greater detail below. Fig. 1 shows an embodiment of an apparatus for recycling waste containing plastic and/or organic material, having a vacuum tank with a rectangular cross sec¬ tion, and Fig. 2 shows a second embodiment of the apparatus accord¬ ing to the invention with a spherical vacuum tank. Modes for Carrying Out the Invention Fig. 1 shows an apparatus labelled as a whole with refer¬ ence number 10, for recycling waste 12 containing plastic and/or organic material. The apparatus has an approximately rectangular vacuum tank 14 depicted in vertical cross sec- tion in Fig. 1 and containing a vacuum chamber 16. The tank 14 has a door not shown that can be opened for loading the waste 12 and subsequently vacuum-tightly reclosed. The vacuum tank 14 is provided with a common vacuum-producing unit that is not part of the invention and is therefore not shown. Four microwave generators 18 are associated with the vacuum chamber 16. As all the microwave generators have the same design, only one is described below. Fur¬ thermore, the vacuum chamber 16 has a feed line 20 for easily ionizable gas such as argon or another noble gas or an inert gas, and a feed line 22 for hydrogen. In addi¬ tion, the vacuum chamber 16 has two discharge lines 24 and 26 in its upper and lower parts, respectively, for gaseous components arising in the vacuum chamber 16. The discharge line 24 is located in the upper part of the vacuum chamber 16 and is provided for components having a low unit weight, whereas the discharge line 26 is located in the lower part of the vacuum chamber 16 and is provided for components ha¬ ving a high unit weight. The microwave generator 18 is a magnetron 28 disposed out¬ side the vacuum chamber 16 and radiating into the vacuum chamber 16 through a radiation tube 30 of a microwave-per¬ meable material that leads into the vacuum chamber 16, where its end is closed. The radiation tube 30 is provided with a microwave-reflecting coating 34 on its side 32 fa¬ cing away from the waste 12. The radiation tube 30 has an open end opposite the closed end, with the magnetron 28 sealed onto the open end. The radiation tube 30 is filled with an electrically insulating gas such as SF6- The microwave generators 18 are distributed over the walls of the vacuum tank 14 as shown in. Fig. 1. Because of the coa¬ ting 34 the radiation is directed toward the waste 12. In the microwave generator 18 shown at the lower left in Fig. l, the coating 34 is accordingly likewise on the lower side. Fig. 2 shows a variant of the invention, with the vacuum tank 14' shown in cross section being spherically designed, but otherwise like the vacuum tank 14. The two discharge lines 24, 26 are each connected via a condenser 36 or 38, respectively, to a collection vessel 40 and 42, respectively. A high-pressure plasma generator 44 is connected outside the vacuum chamber 16 between the two discharge lines 24, 26. This generator 44, as shown, is connected at its input end to the discharge lines 24 and 26 via a bypass 46 and 48, respectively. Its output end 50 serves to divert halogen-free gas that can be torched off or collected. The high-pressure plasma generator 44 is a microwave generator similar to the microwave generators 18 and has a smaller volume in the present embodiment than the microwave generators 18 and therefore produces higher spe¬ cific energy densities. A source 52 for a reaction partner for halogen radicals is connected to the high-pressure plasma generator 44. The reaction partner can be silicon, sodium or the like, as is explained in further detail be¬ low. Finally, the apparatus contains various check valves R and solenoid valves M, the functions of which need not be further described. In Figures 1 and 2 the radiation tubes 30 are designed and adjusted in such a way that the microwave energy radiating through them is directed toward a common focal point in which the waste 12 is to be placed. The apparatus described above works as follows: Waste 12 to be recycled, containing plastic and/or organic material, is loaded into the vacuum chamber 16 and a vacuum is built up in the vacuum chamber. Subsequently, the va¬ cuum is partially broken in that easily ionizable gas, ar¬ gon in the present example, is fed into the vacuum chamber 16. Any other suitable noble or inert gas can be used in- stead of argon. The gas is ionized in the vacuum chamber 16 up to a predetermined energy density with the aid of the magnetrons 28 by admission of microwave energy. The pre¬ determined energy density should preferably lie between three and thirty watts/cm3. By feeding hydrogen from the feed line 22 into the vacuum chamber 16 containing the io¬ nized gas a plasma is ignited in the vacuum chamber, so that the waste 12 is reduced by the action of the plasma and is hydrated by the hydrogen. By the action of the plasma, for example, plastic is instantaneously broken down into its basic components. The gaseous components of the plastic, which come into being during the reduction, are diverted and collected, and the remaining components of the waste are removed from the vacuum chamber in liquid or so¬ lid form. This breakdown of the waste 12 according to the invention is connected with a substantial reduction in vo- lume . The gaseous components diverted via the discharge lines 24 and 26, to be collected at 40 and 42, are cracked outside the vacuum chamber by the high-pressure plasma generator 44 to break up halogen compounds in order that halogens can be removed separately. For practical purposes halogen radi¬ cals arising here are combined with another reaction part¬ ner. This reaction partner is made available by the source 52. Silicon is used as the other reaction partner if the gaseous components consist primarily of fluorine, whereas sodium is used if the gaseous components consist primarily of chlorine. The particular advantage of the method and the apparatus described above consists in that plastic of highly differ¬ ing quality and randomly mixed can be loaded as waste 12 into the vacuum chamber 16 and recycled, and hence must not be sorted beforehand. The method and the apparatus are namely intended particu¬ larly for breaking down plastic waste of all types, truly sorted or randomly mixed, such as plastic waste from re¬ frigerators to be disposed of, into their basic components, which can then be reused. For this purpose, microwave en¬ ergy with high energy density is admitted to the waste, wherein a gas is ionized, with the effect that the gaseous components leave the waste and to build up a plasma under the action of the microwave energy, by which plasma the plastic is ultimately fully broken down into gaseous compo¬ nents that are diverted at 24 and 26 and into a liquid or powdery residue that remains in a waste receptacle 13 and can be removed with the same from the vacuum tank 14.

Claims: Claims 1. A method for recycling waste containing plastic and/or organic material, characterized by the following steps: a) loading the waste into a vacuum chamber and building up a vacuum; b) partially breaking the vacuum by feeding an easily io- nizable gas into the vacuum chamber; c) ionizing the gas in the vacuum chamber up to a pre¬ determined energy density by admitting microwave energy; d) igniting a plasma in the vacuum chamber by feeding hy¬ drogen into the vacuum chamber containing the ionized gas, so that the waste is reduced by the action of the plasma and is hydrated by the hydrogen; e) diverting and collecting gaseous components of the waste that arise during the reduction; and f) removing residual components of the waste in liquid or solid form from the vacuum chamber. 2. The method according to claim 1, characterized in that argon or a similar noble gas, or at least an inert gas, is used as the easily ionizable gas. 3. The method according to claim 1 or 2, characterized in that the gaseous components are cracked outside the vacuum chamber to break up halogen bonds and remove halogens. 4. The method according to claim 3, characterized in that a high-pressure plasma is produced from the gaseous compo¬ nents, to break up the halogen bonds and to combine halogen radicals arising therein with another reaction partner. 5. The method according to claim 4, characterized in that silicon or sodium is used as the other reaction partner if the gaseous components contain primarily fluorine or chlo¬ rine, respectively. 6. An apparatus for conducting the method according to claim 1, characterized by - a vacuum chamber (16) for receiving the waste (12) to be recycled, - a feed line (20) for easily ionizable gas, - at least one microwave generator (18) associated with the vacuum chamber (16) , said generator (18) building up a sufficiently high microwave energy density in the vacuum chamber (16) to ionize the easily ionizable gas and pro¬ duce a plasma, - a feed line (22) for hydrogen, and - at least one discharge line (24, 26) for gaseous compo- nents arising in the vacuum chamber (16) . 7. The apparatus according to claim 6, characterized in that the microwave generator (18) is a magnetron (28) out¬ side the vacuum chamber (16) , said magnetron (28) radiating through a radiation tube (30) of microwave-permeable mate¬ rial leading into the vacuum chamber (16) , where its end is closed. 8. The apparatus according to claim 7 characterized in that the radiation tube (30) is provided with a microwave-re¬ flecting coating (34) on its side (32) facing away from the waste (12) . 9. The apparatus according to claim 7 or 8, characterized in that the radiation tube (30) is filled with an electri- cally insulating gas such as SF6. 10. The apparatus according to any of claims 6 to 9, char¬ acterized in that at least two discharge lines (24, 26) are provided for gaseous components arising in the vacuum cham¬ ber (16) , one (26) in the lower portion of the vacuum cham¬ ber (16) for heavy components having a high unit weight and one (24) in the upper portion of the vacuum chamber (16) for lightweight components having a low unit weight. 11. The apparatus according to claim 10, characterized in that the two discharge lines (24, 26) are each connected via a condenser (36, 38) to a collection vessel (40, 42) . 12. The apparatus according to claim 10 or 11, character¬ ized in that a high-pressure plasma generator (44) is con¬ nected outside the vacuum chamber (16) between both dis¬ charge lines (24, 26). 13. The apparatus according to claim 12, characterized in that at least one source (52) for a reaction partner for halogen radicals is connected to the high-pressure plasma generator (44) . 14. The apparatus according to any of claims 7 to 9, char¬ acterized in that several magnetrons (28) radiating into the vacuum chamber (16) are provided, with the radiation tubes (30) thereof being designed or adjusted such that the microwave energy radiated through said tubes (30) is di- rected toward a common focal point where the waste (12) is to be placed.

Inventors: POESCHL GUENTER, POESCHL, GUENTER
Applicants: POESCHL GUENTER, PPV VERWALTUNGS AG, POESCHL, GUENTER
Application year: 1994
Main classification: C10B19
IPC codes: B01J3, B01J19, C10B55, H05H1